This invention relates to an imager using a solid-state image sensor and a photometric circuit.
With the aim of obtaining a signal for exposure control, one type of prior art imager has a photometric sensor which is independent of an image sensor.
Another imager is known as disclosed in JP-A-59-194575 and it performs exposure control by using a video output signal from a solid-state image sensor adapted to obtain an image signal.
The latter imager having an iris in front of the image sensor integrates the video output signal from the image sensor to calculate a quantity of light incident to the image sensor and controls the iris in accordance with a calculated value to obtain optimum exposure.
Disadvantageously, the former prior art imager requires the photometric sensor which is independent of a image sensor.
The latter prior art imager does not require an independent photometric sensor, but because of the use of an integration signal of the video signal from the image sensor as a signal for exposure control, a current representative of the image signal read out of the image sensor is liable to be disturbed by a photometric circuit.